Compact Cascaded-Spiral-Patch EBG Structure for Broadband SSN Mitigation in WLAN Applications

A compact cascaded-spiral-patch electromagnetic bandgap (CSP-EBG) structure for wideband simultaneously switching noise suppression is proposed. Instead of using double open stubs to provide dual-band noise suppression for a wireless local area network (WLAN), the proposed CSP-EBG structure offers an even wider bandgap, covering multiple adjacent WLAN bands from 2.4 to 6 GHz. A 1-D equivalent circuit model is proposed and validated by full-wave simulation and measurement. The circuit model could also be adopted to investigate design concepts, optimizing the EBG design by the theory of stepped-impedance resonator. The stopband of the proposed EBG structure covers a frequency range from 2.4 to 6.4 GHz with 91% fractional bandwidth (FBW). It not only provides three times wider FBW than single and double open stubs EBG but also occupies 95% smaller unit-cell size than double open stubs EBG and four times smaller than the mushroom EBG.